Potassium bromate has been used worldwide since the 1910s when it was recommended as a bread improver in the United States. In Japan, there is a regulation for use of potassium bromate, stating that “potassium bromate is limited to use for yeast leavened bakery products in an amount of up to 0.03 g (as bromate) per kg of wheat flour (i.e., 30 ppm based on wheat flour) and should be decomposed or removed before completing final products,” that is, potassium bromate must not remain in the products after baking.
In conventional techniques, prevention of residual bromate in bakery products has been accomplished, either by using sufficient time for fermentation and baking of a dough to ensure complete chemical reaction of bromate or by incorporating a reduced amount of potassium bromate, or both.
The inventors of the present invention have already developed a method for reduction of residual bromate in bakery products by incorporating ascorbic acid (see, e.g., JP 8-116857 A).
The limitation “bromate should be decomposed or removed” or “bromate must not remain” in the Japanese regulation is intended to mean that bromate should not be detectable when measured by the most sensitive analysis at the time of the measurement, i.e., that bromate is below the detection limit. In view of this limitation, the inventors of the present invention have attempted to incorporate ferrous sulfate in the step of preparing a dough using potassium bromate and have succeeded in reducing residual bromate in bakery products to less than 3 ppb, a non-detectable level as measured by their developed ultra-sensitive HPLC (high performance liquid chromatography) analysis with a detection limit of 3 ppb for bromate in the baked breads (see, e.g., Japanese Patent No. 3131898).
However, the term “free from residual bromate” or “prevention of residual bromate” as used herein is intended to mean that bromate does not remain in an amount of 0.5 ppb or more, the “detection limit for bromate” as measured by further improved state-of-the-art HPLC analysis at the filing of the present invention.
However, the above conventional techniques do not confirm their efficacy for removal or significant reduction of residual bromate in the resulting breads of the pullman type, and particularly do not meet the criterion of less than 0.5 ppb at the filing of the present invention. They also fail to disclose the incorporation of potassium bromate as an aqueous solution. Further, in these conventional techniques, ferrous sulfate is incorporated in an amount of 50 ppm to 370 ppm based on total wheat flour required to prepare a dough, which amount significantly exceeds the range-acceptable for the breads of the present invention to maintain the loaf volume, flavor and taste of breads.
There has been a need to develop a method for making pullman type breads, which allows improvements in the quality of baked breads by incorporating potassium bromate into a bread dough and which provides pullman type breads completely free from the incorporated bromate or with a bromate content reduced to less than 0.5 ppb, the detection limit for bromate.